When the world lost comedy legend Robin Williams back in August, Billy Crystal lost his “dearest friend.” During his Tonight Show appearance on Thursday, Crystal and host Jimmy Fallon paid tribute to the late comedic genius, swapping their favorite first-hand Williams stories.

In the above clip, Fallon commends Crystal for his brave, touching Emmy tribute to Williams. “It was really a hard thing,” Crystal reflects, noting that the entire crowd was feeling “the same sadness, bewilderment, frustration and this overall ‘What?!’

“It was only two weeks after. And to try to do him justice for myself and for the audience around the world, really, in two minutes was the task. I’ve given eulogies before, sadly, for a lot of people I love, but nobody on television.”

Fallon lightens the mood by telling a hilarious story about being on a bus filled with comedy icons – Williams, Martin Short, Rob Reiner, Jon Lovitz and Danny DeVito – as they traveled to Washington D.C. for the Kennedy Center Honors. Before they could enter the building, they encountered a bomb-sniffing dog, leading to a round of self-deprecating punchlines about their respective film flops.

“Oh, I hope there’s no copies of my movies on this bus!” Fallon says, impersonating Williams. “Quick, everyone throw Popeye out the window!”

Crystal closes with some more reflections on Williams, whom he calls “the greatest mind I’ve ever been around – because it was so terrifyingly fast.” After reminiscing about their hours of late night phone calls filled with improvisation (“We were like two jazz musicians who got new horns”), Crystal offers an anecdote about Williams getting a stern response from presidential candidate Michael Dukakis during the second Comic Relief event in 1988.